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Fig. 13.—a. Egg of the Dog, With The Vitelline Membrane Burst, So As to Give Exit To the Yelk, The Germinal Vesicle (a), And Its Included Spot (b). BC D. E F. Successive Changes of the Yelk Indicated in the Text. After Bischoff. Fig. 14.—earliest Rudiment of the Dog. B. Rudiment Further Advanced, Showing the Foundations of The Head, Tail, And Vertebral Column. C. The Very Young Puppy, With Attached Ends of The Yelk-sac and Allantois, And Invested in the Amnion. Fig. 15.—a. Human Ovum (after Kolliker). A. Germinal Vesicle. B. Germinal Spot. B. A Very Early Condition of Man, With Yelk-sac, Allantois, and Amnion (original). C. A More Advanced Stage (after Kolliker), Compare Fig. 13, C. Fig. 16.—front and Side Views of the Bony Pelvis Of Man, The Gorilla and Gibbon: Reduced from Drawings Made From Nature, of The Same Absolute Length, by Mr. Waterhouse Hawkins. Fig. 17.—sections of the Skulls Of Man and Various Apes, Drawn So As to Give the Cerebral Cavity The Same Length in Each Case, Thereby Displaying the Varying Proportions of The Facial Bones. The Line 'b' Indicates the Plane of The Tentorium, Which Separates The Cerebrum From the Cerebellum; 'd', The Axis of The Occipital Outlet Of The Skull. The Extent of Cerebral Cavity Behind 'c', Which is a Perpendicular Erected on 'b' at the Point Where The Tentorium is Attached Posteriorly, Indicates the Degree to Which The Cerebrum Overlaps The Cerebellum—the Space Occupied by Which is Roughly Indicated By the Dark Shading. In Comparing These Diagrams, It Must Be Recollected, That Figures on So Small a Scale As These Simply Exemplify the Statements in The Text, The Proof of Which is to Be Found in the Objects Themselves. Fig. 18.—lateral Views, of the Same Length, Of The Upper Jaws of Various Primates. 'i', Incisors; 'c', Canines' 'pm', Premolars; 'm', Molars. A Line is Drawn Through the First Molar of Man, 'gorilla', 'cynocephalus', and 'cebus', And the Grinding Surface of The Second Molar is Shown in Each, Its Anterior and Internal Angle Being Just Above The 'm' of 'm2'. Fig. 19—the Skeleton of the Hand and Foot Of Man Reduced From Dr. Carter's Drawings in Gray's 'anatomy.' the Hand is Drawn To A Larger Scale Than the Foot. The Line 'a A' in The Hand Indicates The Boundary Between the Carpus and The Metacarpus; 'b B' That Between The Latter and the Proximal Phalanges; 'c C' Marks The Ends of The Distal Phalanges. The Line "a' A'" in The Foot Indicates The Boundary Between The Tarsus and Metatarsus; "b' B'" Marks That Between the Metatarsus And the Proximal Phalanges; and "c' C'" Bounds The Ends of The Distal Phalanges; 'ca', the Calcaneum; 'as', The Astragalus; 'sc', The Scaphoid Bone in the Tarsus. Fig 20.—foot of Man, Gorilla, and Orang-utan Of the Same Absolute Length, to Show the Differences in Proportion of Each. Letters As in Fig. 18. Reduced from Original Drawings by Mr. Waterhouse Hawkins. Fig. 21.—drawings of the Internal Casts Of a Man's And Of a Chimpanzee's Skull, of the Same Absolute Length, and Placed In Corresponding Positions. 'a'. Cerebrum; 'b'. Cerebellum. The Former Drawing is Taken from a Cast in the Museum of The Royal College Of Surgeons, the Latter from The Photograph of The Cast Of a Chimpanzee's Skull, Which Illustrates the Paper by Mr. Marshall 'on The Brain of The Chimpanzee' in the 'natural History Review' for July, 1861. The Sharper Definition of the Lower Edge Of The Cast Of The Cerebral Chamber in The Chimpanzee Arises from the Circumstance That The Tentorium Remained In That Skull and Not in the Man's. The Cast More Accurately Represents The Brain in Chimpanzee Than In the Man; and The Great Backward Projection Of the Posterior Lobes of The Cerebrum Of The Former, Beyond The Cerebellum, is Conspicuous. Fig. 22.—drawings of the Cerebral Hemispheres Of a Man And of a Chimpanzee Of the Same Length, in Order to Show The Relative Proportions of the Parts: The Former Taken from a Specimen, Which Mr. Flower, Conservator of the Museum Of The Royal College Of Surgeons, Was Good Enough to Dissect for Me; the Latter, from The Photograph Of A Similarly Dissected Chimpanzee's Brain, Given in Mr. Marshall's Paper Above Referred To. 'a', Posterior Lobe; 'b', Lateral Ventricle; 'c', Posterior Cornu; 'x', the Hippocampus Minor. |
THE question of questions for mankind—the problem which underlies all others, and is more deeply interesting than any other—is the ascertainment of the place which Man occupies in nature and of his relations to the universe of things. Whence our race has come; what are the limits of our power over nature, and of nature's power over us; to what goal we are tending; are the problems which present themselves anew and with undiminished interest to every man born into the world. Most of us, shrinking from the difficulties and dangers which beset the seeker after original answers to these riddles, are contented to ignore them altogether, or to smother the investigating spirit under the featherbed of respected and respectable tradition. But, in every age, one or two restless spirits, blessed with that constructive genius, which can only build on a secure foundation, or cursed with the spirit of mere scepticism, are unable to follow in the well-worn and comfortable track of their forefathers and contemporaries, and unmindful of thorns and stumbling-blocks, strike out into paths of their own. The sceptics end in the infidelity which asserts the problem to be insoluble, or in the atheism which denies the existence of any orderly progress and governance of things: the men of genius propound solutions which grow into systems of Theology or of Philosophy, or veiled in musical language which suggests more than it asserts, take the shape of the Poetry of an epoch.
Each such answer to the great question, invariably asserted by the followers of its propounder, if not by himself, to be complete and final, remains in high authority and esteem, it may be for one century, or it may be for twenty: but, as invariably, Time proves each reply to have been a mere approximation to the truth—tolerable chiefly on account of the ignorance of those by whom it was accepted, and wholly intolerable when tested by the larger knowledge of their successors.
In a well-worn metaphor, a parallel is drawn between the life of man and the metamorphosis of the caterpillar into the butterfly; but the comparison may be more just as well as more novel, if for its former term we take the mental progress of the race. History shows that the human mind, fed by constant accessions of knowledge, periodically grows too large for its theoretical coverings, and bursts them asunder to appear in new habiliments, as the feeding and growing grub, at intervals, casts its too narrow skin and assumes another, itself but temporary. Truly the imago state of Man seems to be terribly distant, but every moult is a step gained, and of such there have been many.
Since the revival of learning, whereby the Western races of Europe were enabled to enter upon that progress towards true knowledge, which was commenced by the philosophers of Greece, but was almost arrested in subsequent long ages of intellectual stagnation, or, at most, gyration, the human larva has been feeding vigorously, and moulting in proportion. A skin of some dimension was cast in the 16th century, and another towards the end of the 18th, while, within the last fifty years, the extraordinary growth of every department of physical science has spread among us mental food of so nutritious and stimulating a character that a new ecdysis seems imminent. But this is a process not unusually accompanied by many throes and some sickness and debility, or, it may be, by graver disturbances; so that every good citizen must feel bound to facilitate the process, and even if he have nothing but a scalpel to work withal, to ease the cracking integument to the best of his ability.
In this duty lies my excuse for the publication of these essays. For it will be admitted that some knowledge of man's position in the animate world is an indispensable preliminary to the proper understanding of his relations to the universe—and this again resolves itself, in the long run, into an inquiry into the nature and the closeness of the ties which connect him with those singular creatures whose history 1 has been sketched in the preceding pages.
The importance of such an inquiry is indeed intuitively manifest Brought face to face with these blurred copies of himself, the least thoughtful of men is conscious of a certain shock, due perhaps, not so much to disgust at the aspect of what looks like an insulting caricature, as to the awakening of a sudden and profound mistrust of time-honoured theories and strongly-rooted prejudices regarding his own position in nature, and his relations to the under-world of life; while that which remains a dim suspicion for the unthinking, becomes a vast argument, fraught with the deepest consequences, for all who are acquainted with the recent progress of the anatomical and physiological sciences.
I now propose briefly to unfold that argument, and to set forth, in a form intelligible to those who possess no special acquaintance with anatomical science, the chief facts upon which all conclusions respecting the nature and the extent of the bonds which connect man with the brute world must be based: I shall then indicate the one immediate conclusion which, in my judgment, is justified by those facts, and I shall finally discuss the bearing of that conclusion upon the hypotheses which have been entertained respecting the Origin of Man.
The facts to which I would first direct the reader's attention, though ignored by many of the professed instructors of the public mind, are easy of demonstration and are universally agreed to by men of science; while their significance is so great, that whoso has duly pondered over them will, I think, find little to startle him in the other revelations of Biology. I refer to those facts which have been made known by the study of Development.
It is a truth of very wide, if not of universal, application, that every living creature commences its existence under a form different from, and simpler than, that which it eventually attains.